This study was aimed to provide the pharmacological basis for the medicinal use of Lepidium sativum in diarrhea using in vivo and in vitro assays. The seed extract of Lepidium sativum (Ls.Cr) at 100 and 300 mg/kg inhibited castor oil-induced diarrhea in rats. In isolated rat ileum, Ls.Cr (0.01-5 mg/mL) reversed carbachol (CCh, 1 µM) and K(+) (80 mM)-induced contractions with higher potency against CCh, similar to dicyclomine. Preincubation of rat ileum with a lower concentration of Ls.Cr (0.03 mg/mL) caused a rightward parallel shift in the concentration-response curves (CRCs) of CCh without suppression of the maximum response, while at the next higher concentration (0.1 mg/mL), it produced a non-parallel rightward shift with suppression of the maximum response, similar to that of dicyclomine. Ls.Cr shifted the CRCs of Ca(++) to the right with suppression of the maximum response, similar to verapamil. These data suggest that Lepidium sativum seed extract possesses antidiarrheal and spasmolytic activities mediated possibly through dual blockade of muscarinic receptors and Ca(++) channels, though additional mechanism(s) cannot be ruled out and this study explains its medicinal use in diarrhea and abdominal cramps.